It's hard to remember, but back in the early 1990s there was a debate about how nations should emerge from Communism -- the Russian way or the Chinese way. The Russians did political and economic reform together. The Chinese just did economic reform.

Reality doesn't allow clean experiments, but the Chinese model has won in the court of public opinion. China's success has given autocracy a legitimacy it lacked. In each of the past eight years, according to Freedom House, the number of countries that moved in an autocratic direction has outnumbered those that moved in a democratic one.

When you look at autocracies, you notice that many have undergone a similar life cycle. Autocrats may start out thinking they will be benevolent dictators. They may start out flirting with the West and talking about liberalizing reforms. But their regimes are almost always corrupt and inefficient. To stay on top, autocrats have to whip up nationalistic furies. They have to be aggressive in their regions to keep the country united on a permanent war footing. Unstable within, autocracies have to be radioactive abroad. Autocrats may start out claiming to be their country's Deng Xiaoping, but they often end up more like Robert Mugabe.

Dealing with thuggish radioactive autocracies will probably be the great foreign policy challenge of the next decade. Aggressive autocratic rulers will challenge national borders and inflame regional rivalries. They will exacerbate ethnic tensions and gnaw at the world order. They have already made the world a more ornery place.

How will the United States respond? President Barack Obama laid out his approach in a speech at West Point this week. He argued persuasively that the U.S. will have to do a lot more to mobilize democracies to take effective collective action against autocratic aggression.

Moreover, his administration does champion democracy. On the same day Obama spoke, his ambassador to the United Nations, Samantha Power, gave a great commencement speech at Harvard's Kennedy School of Government explaining why democracy promotion has to be at the core of U.S. foreign policy.

But the president's attitude seems to me in some ways ill-suited for the autocratic challenge. First, he might have the balance wrong between overreach and underreach.

Perhaps drawing on the Iraq example, Obama believes America's problems have not been caused by too much restraint, but by overreach and hubris.

In the larger frame of history, this is a half-truth. In the 1920s and '30s, for example, Americans were in a retrenching mood, like today. The result was a leaderless world, the gradual decay of the world order and eventually World War II.

As Robert Kagan shows in a brilliant essay in The New Republic, for the past 70 years, U.S. policymakers have understood that underreach can lead to catastrophe, too. Presidents assertively tended the international garden so that small problems didn't turn into big ones, even when core national interests were not at stake.

In the 1990s, for example, President George H.W. Bush and President Bill Clinton took military action roughly every 17 months to restrain dictators, spread democracy and preserve international norms.

This sort of forward-leaning interventionist garden-tending will be even more necessary in an age of assertive autocracies.

If the U.S. restricts intervention to "core interests," as Obama suggests, if it neglects constant garden-tending, the thugs will grab and grab and eventually there will be horrendous conflagrations.

America's assertive responses will not need to be military; they rarely will be. But they'll need to be simple, strong acts of deterrence to preserve order.

As Leon Wieseltier notes, if Obama spoke in Kiev on his coming European trip, that alone would be an assertive gesture, like JFK going to Berlin.

Second, Obama underestimates how much the logic of force will remain central in the years ahead. It would be nice if autocrats thought in terms of international norms or according to the rational calculus of cost benefit analysis. But autocrats got where they are because they are primitives who perceive the world through the ancient calculus of power and force.

What we perceive as prudence, they perceive as weakness. Absent clear and forceful counterpressure, they will cross red lines that the current or future president will have to enforce.

For most of the past 70 years, the U.S. had a two-level foreign policy. On top, U.S. diplomats built multilateral coalitions to extend democracy. But at the bottom level, U.S. presidents understood their responsibility as the world's enforcer, occasionally operating according to the logic of menace and force.

If Obama departs from that tradition and takes away that bottom level -- for fear of overreach, or in a quest for normalcy, or out of an excessive belief in the limits of his own power -- then he will undermine the top level that he admires. The autocrats will drag the world into an ungodly mess.